Nitroaldol reaction catalyzed by arylhydrazone di- and triorganotin(IV) complexes

Two known organotin(IV) complexes, [Sn(C6H5)3HL1] (1, H2L1 = 2-(2-(2,4-dioxopentan-3-ylidene)hydrazinyl)benzoic acid) and [Sn(C2H5)2(1κO,2κO-H3L2) (1κO2-H3L2) (μ3-O)]2 (2, H4L2 = 2-(2-(2,4,6-trioxotetrahydropyrimidin-5(2H)-ylidene)hydrazinyl)benzoic acid) were synthesized. Both compounds 1 and 2 act as homogenous catalysts for the diastereoselective nitroaldol (Henry) reaction of aliphatic and aromatic aldehydes with nitroethane in different solvents such as dichloromethane, acetonitrile or methanol. Complex 2 was found to be the more efficient catalyst for the Henry reaction in methanol, producing β-nitroalcohols with good yields (65−89%) and diastereoselectivities (syn/anti 72:28−77:23). © 2017 Elsevier B.V.